1. Field of the Invention
The present invention relates to a thin film magnetic head magnetically recording by use of, for example, a perpendicular recording system, and a method of manufacturing the same.
2. Description of the Related Art
In recent years, magnetic recording apparatuses such as, for example, hard disk drives which record information on hard disks have been in widespread use as information recording sources. In the development of hard disk drives, an improvement in performance of thin film magnetic heads has been sought in accordance with an increase in the areal density of the hard disks. As magnetic recording systems applicable to thin film magnetic heads, for example, a longitudinal recording system that a signal magnetic field is oriented in an in-plane direction (a longitudinal direction) of a hard disk and a perpendicular recording system that the signal magnetic field is oriented in a direction perpendicular to a surface of the hard disk are well known. At present, the longitudinal recording system is widely used, but in consideration of market forces in accordance with an improvement in areal density, the perpendicular recording system instead of the longitudinal recording system holds promise for future, because the perpendicular recording system can obtain an advantage that higher liner recording density can be achieved, and a recording medium in which data has been already recorded has resistance to thermal decay effects.
As recording modes using the perpendicular recording system, for example, a mode in which recording on a single layer hard disk is performed by a main part through using a head (ring type head) facing each other with a gap in between on a side of an end and being magnetically coupled to each other on a side of the other end, or a mode in which recording on a two-layer hard disk is performed by a main part through using a head (single-pole type head) being disposed perpendicular to the hard disk has been proposed. In these modes, based upon a point that the mode using a combination of the single-pole type head and the two-layer hard disk has superior resistance to thermal decay, the mode becomes a focus of attention as a mode which can improve the performance of thin film magnetic heads.
The perpendicular recording system thin film magnetic head comprises a single-pole type head and a thin film coil generating a magnetic flux. The single-pole type head includes a pole layer emitting the magnetic flux generated by the thin film coil toward the hard disk, and a return magnetic layer where the magnetic flux emitted from the pole layer to magnetize the hard disk is returned, and an end surface of the pole layer and an end surface of the return magnetic layer are exposed to an air bearing surface (recording-medium-facing surface) facing the hard disk. The return magnetic layer is magnetically coupled to the pole layer, for example, on a side away from the air bearing surface, and is generally called “return yoke”.
In the perpendicular recording system thin film magnetic head, in a state in which the single-pole type head faces the hard disk, when the magnetic flux generated by the thin film coil is emitted from the pole layer toward the hard disk, the magnetic flux is returned to the return magnetic layer through the hard disk. At this time, a perpendicular magnetic field for recording is generated by the magnetic flux emitted from the pole layer, and the perpendicular magnetic field magnetizes the hard disk so as to record information on the hard disk.
In order to improve recording performance of the perpendicular recording system thin film magnetic head, for example, it is required to inhibit an influence of a problem called “track erasing” as much as possible. Track erasing mainly means a phenomenon in which during recording to a target track on the hard disk, information recorded on other tracks except for the target track is erased without intention. When track erasing occurs, information cannot be stably recorded on the hard disk, so the reliability of magnetic recording decreases.
However, in a conventional perpendicular recording system thin film magnetic head, measures to inhibit the occurrence of track erasing mainly resulting from a returning mechanism of the magnetic flux during recording is not sufficient yet.